Cameron Douglas, the 31-year-old son of movie star Michael Douglas and the grandson of screen legend Kirk Douglas, was yesterday handed a five-year jail sentence for drug dealing. New York judge Richard Berman handed out the term, which was less than the expected minimum sentence, after a series of heartfelt pleas from members of the Douglas family. Berman said the sentence was Cameron Douglas's "last chance to make it".

His father was in court to watch sentence being passed after details of a letter he wrote to the judge were released to the public. In the five-page handwritten missive, Michael Douglas, who won an Oscar for his role as Gordon Gekko in the film Wall Street, described his son's struggle with addiction and blamed the pressure of living with a celebrity name. As the son of Spartacus star Kirk Douglas, Michael wrote, he was painfully aware of the weight of familial fame. "I have some idea of the pressure of finding your own identity with a famous father. I'm not sure I can comprehend it with two generations to deal with," he wrote.

The letter provided a rare glimpse into the private life of a family who have carried a Hollywood A-list name for two generations. In his missive, he blamed his "bad marriage", his parenting skills and his film career for making him an absentee father. That led Cameron Douglas to abuse drugs from an early age. "I don't want to burden you with a litany of my son, Cameron's, rehab history, beginning at 13 … We do know, however, that genes, family and peer pressure are all a strong influence on a substance abuser," the letter said.

In one touching segment, Michael Douglas said that spending time in jail had left Cameron clean of drugs and allowed father and son to connect. "For the past eight months I have cherished my two hours a week in-person conversation with Cameron [at the jail]. He's sober! I get to witness the wonderful young man he can be," he wrote.

Other members of the family also wrote letters of support. His stepmother, British actress Catherine Zeta-Jones, praised his behaviour in the family. "What is wrong is wrong, but may all these positive attitudes prevail," she wrote. Kirk Douglas, now 93, said it was his dying wish to see his grandson turn his life around. "I am convinced that Cameron could be a fine actor and a person that cares for others. I hope I can see that happen before I die," he said.

Cameron Douglas, a part-time actor and DJ, had admitted selling cocaine and methamphetamine at a hotel in New York's Meatpacking district. The offence usually carries a minimum of 10 years in jail, unless the judge decides on leniency. Cameron Douglas's lawyers had argued he had only been dealing drugs in order to finance his crippling heroin habit.

In addition to the jail time, Cameron Douglas must also pay a $25,000 fine and do 450 hours' community service. Once out of jail, he also faces a five years in a supervised release programme.